Site Description Mining began at Cwmbyrgwm Colliery began before 1820 and expanded with the development of the British Ironworks in 1827. There is a rich mining landscape around the remains of a scheduled water-balance headgear (NPRN 85075), including a brick chimney (NPRN 85073) of around 1880, waste tips, several oval shafts (NPRNs 85074, 85075), two water power dams and tramroad routes. The colliery is depicted as in-use on Ordnance Survey 25in map first edition of 1880 and as disused on the second edition of 1901.